SAME

Cross-Reference to Related Applications

[0001] The present application claims priority from Australian Provisional Patent Application No. 2012904462 filed on 12 October 2012, the content of which is incorporated herein by reference.

Field Of Invention

[0002] The present invention relates to a drying process, system and a dried food obtained using the same.

Background

[0003] Drying of food generally requires a slow drying process using a low temperature such as an exposure of between 250°C to 350°C for 30 to 60 minutes. In the event that a higher temperature is used to dry the food in order to speed up the drying process or to increase throughput, the dried food exhibits substantial nutritional losses. Furthermore, if the food is dried to a point having a moisture content of under 6% using such a high temperature, the digestibility of the dried food is compromised.

[0004] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Summary of Invention

[0005] In a first aspect there is provided a method of drying a food comprising:

a) drying the food at a temperature between about 350°C and about 550°C to produce a partially dried food, wherein the partially dried food has a moisture content between about 20% and about 40%; and b) drying the partially dried food at a temperature between about 40°C and about 350°C to produce a dried food, wherein the dried food has a moisture content between about 20% and about 3%.

[0006] In certain embodiments, step a) is carried out in a first dryer and step b) is carried out in a second dryer.

[0007] In certain embodiments, the first and second dryer are used in a continuous drying process.

[0008] In certain embodiments, the method comprises providing a continuous supply of the food to the first dryer, wherein the partially dried food from the first dryer is continuously provided to the second dryer.

[0009] In certain embodiments, the method further comprises moving the partially dried food from the first dryer to the second dryer using a conveyor.

[0010] In certain embodiments, the first dryer directly contacts the food with an inert gas having the temperature of between about 350°C and about 550°C to dry the food.

[0011] In certain embodiments, the second dryer directly contacts the partially dried food with an inert gas having the temperature between about 40°C and about 350°C to dry the partially dried food.

[0012] In certain embodiments, the inert gas is air.

[0013] In certain embodiments, the first dryer is selected from the group consisting of a flash dryer, a fluid bed dryer, an infra-red dryer, a drum dryer, a ring dryer, a spray dryer, and a bed dryer. [0014] In certain embodiments, the second dryer is selected from the group consisting of a flash dryer, a fluid bed dryer, an infra-red dryer, a drum dryer, a ring dryer, a spray dryer, and a bed dryer.

[0015] In certain embodiments, the method comprises the step of comminuting the partially dry food.

[0016] In certain embodiments, the method comprises the step of the second dryer comminuting the partially dry food.

[0017] In certain embodiments, the moisture content of the partially dried food and/or the dried food is determined using a moisture sensor.

[0018] In certain embodiments, step a) and/or step b) are carried out for a predetermined period of time.

[0019] In certain embodiments, step a) is performed between about 3 seconds to about 5 seconds.

[0020] In certain embodiments, step a) is performed for about 4 seconds.

[0021] In certain embodiments, step b) is performed between about 3 second to about 4 seconds.

[0022] In certain embodiments, step b) is performed for about 3.5 seconds.

[0023] In certain embodiments, the method comprises the step of screening the partially dried food such that a first portion of the partially dried food is not subject to step ^b )- [0024] In certain embodiments, the first portion of the partially dried food not subject to step b) comprises ash.

[0025] In certain embodiments, the first portion of the partially dried food not subject to step b) comprises bone.

[0026] In certain embodiments, the first portion of the partially dried food not subject to step b) comprises non-nutritional material.

[0027] In certain embodiments, the method comprises introducing one or more additional food ingredients to the partially dried food prior to step b).

[0028] In certain embodiments, the one or more additional food ingredients are selected from the group consisting of an alcohol, a herb, garlic, ginger, saffron, onion, a colouring agent, a phenol, a polyphenol, a fragrant essential oil, an aromatic vegetable organic matter, a bacteria, and food compatible compounds.

[0029] In certain embodiments, the temperature of step a) is between about 400°C and about 500°C.

[0030] In certain embodiments, the temperature of step a) is about 450°C.

[0031] In certain embodiments, the moisture content of the partially dried food is between about 20% to 30%

[0032] In certain embodiments, the moisture content of the partially dried food is about 25%.

[0033] In certain embodiments, the temperature of step b) is between about 100°C and about 350°C. [0034] In certain embodiments, the moisture content of the dried food is between about 5% to 15%.

[0035] In certain embodiments, the moisture content of the dried food is between about 8% to 10%.

[0036] In certain embodiments, the moisture content of the dried food is about 8%.

[0037] In a second aspect there is provided a dried food obtained according to the method of the first aspect.

[0038] In a third aspect there is provided a system for drying food, wherein the system includes:

a first dryer for drying the food at a temperature between about 350°C and about 550°C to produce a partially dried food, wherein the partially dried food has a moisture content between about 20% and about 30%; and

a second dryer for drying the partially dried food at a temperature between about 40°C and about 350°C to produce a dried food, wherein the dried food has a moisture content between about 20% and about 3%.

[0039] In certain embodiments, the system is adapted to perform the method of the first aspect.

[0040] Other aspects and embodiments will be appreciated throughout the detailed description herein.

Brief Description of the Drawings

[0041] Example embodiments should become apparent from the following description, which is given by way of example only, of at least one preferred but non- limiting embodiment, described in connection with the accompanying figures. [0042] Figure 1 illustrates a system diagram of an example system for drying organic matter;

[0043] Figure 2 illustrates a system diagram of a further example system for drying organic matter;

[0044] Figure 3 illustrates a table for a first example of the preparation of dried food;

[0045] Figure 4 illustrates a table for a second example of a comparison of different methods of drying food;

[0046] Figure 4 illustrates a table for a third example of a comparison of different methods of drying food;

[0047] Figure 5 illustrates a table for a fourth example of a comparison of different methods of drying food;

[0048] Figure 6 illustrates a table for a fifth example of a comparison of dried food;

[0049] Figure 7 illustrates a table for a sixth example of a comparison of different methods of drying food; and

[0050] Figure 8 illustrates a table for a seventh example of a sieve test of a dried food using different drying methods.

Detailed Description of the Preferred Embodiments

[0051] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element. [0052] As used herein the term "food" includes any nutritious substance that a subject eats or drinks, or that plants absorb, such as fertilizer, in order to maintain life and growth.

[0053] As used herein the term "nutrient" includes a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment, and includes carbohydrates, fats, proteins, amino acids, vitamins, and inorganic chemical compounds such as dietary minerals.

[0054] As used herein the term "subject" includes humans, primates, livestock (eg. sheep, pigs, cattle, horses, donkeys), laboratory test animals (eg. mice, rabbits, rats, guinea pigs), companion animals (eg. dogs, cats), show animals (eg. dogs, cats, pigs, cattle, sheep, horses) fish, Crustacea, molluscs, other marine animals and captive wild animals (eg. foxes, kangaroos, deer).

[0055J The following modes, given by way of example only, are described in order to provide a more precise understanding of the subject matter of a preferred embodiment or embodiments.

[0056] In one aspect the present invention relates to a method of drying food. The method includes a first drying step of drying the food at a temperature between about 350°C and about 550°C to produce a partially dried food such that the partially dried food has a moisture content between about 20% and about 40%. The method then includes a second step drying step of drying the partially dried food at a temperature between about 40°C and about 350°C to produce a dried food such that the dried food has a moisture content between about 20% and about 3%.

[0057] By performing a two stage drying process substantial advantages can be achieved. It has been found that exposing the food to the high heat in the first drying step until the required moisture content is obtained results in retaining substantial nutrients that are otherwise lost using traditional single step drying processes. This has been identified because in the first step the existing high water content in the partially dried food substantially protects a higher proportion portion of the nutrients from being substantially damaged compared to other drying methods currently in use. As the second drying step is performed at a lower temperature relative to the first drying step, the nutritional value is retained compared to traditional single step drying processes. Furthermore, as the first drying step can be performed more quickly due to exposing the food to a higher than normal drying temperature, an increase in production of dried food can be achieved.

[0058] In a preferred form, the temperature of the first drying step is between about 400°C and about 500°C. In a more preferred form, the temperature of the second drying step is about 450°C. In a preferred form, the temperature of the second drying step is between about 100°C and about 350°C. In a preferred form, the moisture content of the partially dried food is between about 20% and about 30%. In an event more preferred form, the moisture content of the partially dried food is about 25%.

[0059] In a preferred form, the moisture content of the dried food which is obtained from the second drying step is between about 5% to 15%. In a more preferred form, the moisture content of the dried food is between about 8% to 10%. In an even more preferred form, the moisture content of the dried food is about 8%.

[0060] Referring to Figure 1 , there is shown a system diagram of a system 100 for performing the above method. In particular, the system 100 includes a first dryer 110 and a second dryer 120. The first dryer 110 is used to dry the food 130 to obtain the partially dried food 140. The partially dried food 140 is then moved to the second dryer 120 for further drying at the lower temperature to obtain the dried food 160. It will be appreciated from Figure 1 that the first and second dryers 1 10, 120 are separate dryers.

[0061] As shown in Figure 1 , the system 100 can include a conveyor 150 which moves the partially dried material 140 from the first dryer 110 to the second dryer 120 in a continuous drying process. In particular, a continuous supply of the food 130 is provided to the first dryer 1 10 and the partially dried food 140 from the first dryer 1 10 is continuously provided to the second dryer 120 such that a serial/tandem drying process occurs. [0062] The first and second dryer 1 10, 120 can use a heated insert gas to directly contact the food 130 or the partially dried food 140 respectively. In a preferred form, the inert gas is air. Preferably, the insert gas is not super-saturated.

[0063] The first dryer 110 and/or the second dryer 120 can be a flash dryer, a fluid bed dryer, an infra-red dryer, a drum dryer, a ring dryer, a spray dryer, and a bed dryer. In one form, the first dryer 1 10 and/or the second dryer 120 can be a dryer as described in US Patent No. 5,105,560, the contents of which is herein incorporated by reference.

[0064] The method of drying can includes comminuting the partially dry food 140 which exits the first dryer 1 10. In a preferred form, comminuting the partially dry food can be performed by the second dryer 120 whilst performing the second drying phase. However, it is possible that a separate comminuting machine or the like can be used to comminute the partially dried food which is performed separately to the second dryer 120.

[0065] The drying method can use a moisture sensor to determine the moisture content of the partially dried food 140 in the first drying step and/or the dried food 160 in the second drying step. In one form, the moisture meter may be a component of the first dryer 1 10 and/or the second dryer 120. Separate moisture sensors can be used for each drying step. In an alternative arrangement, the first drying step and/or the can be performed a predetermined period of time in order to obtain partially dried and dried food respectively with the required moisture content. This arrangement requires initially determining the time period that the first drying step and/or the second drying step can be performed in order to obtain the required moisture content. Once the predetermined time period(s) have been determined, the first and second dryer 1 10, 120 and/or the conveyor 150 can be configured to apply the first and/or second drying steps for the predetermined time period(s). The predetermined time periods can be monitored using one or more exposure timers. In one form, the predetermined time period for the first drying process to be performed to food can be between about 3 seconds to about 5 seconds, and more preferably about 4 seconds. The predetermined time period for the second drying process to be performed to the partially dried food is between about 3 seconds to 4 seconds, and more preferably about 3.5 seconds.

[0066] Referring to Figure 2 there is shown an alternate example of a system 200 for drying food, wherein the system 200 includes a screen 170 which can be used to screen the partially dried food 140 that exits the first dryer 1 10 such that a first portion of the partially dried food 140B is not subject to the second drying step performed by the second dryer 120, whereas a second portion 140A is subject to the second drying step. The portion of partially dried food 140A which is separated and not subject to the second drying step comprises at least one of ash, bone and non-nutritional material such as plastic, paper, carapace and other oversized material. This screening step is used such that smaller portions of the partially dried food 140 are then provided to the second dryer 120 as well removing portions of the partially dried food 140A which have substantially no nutritional benefits. As shown in Figure 2, the conveyor 150 of the system 200 includes a first conveyor 150A and a second conveyor 150B to convey the partially dried food to and from the screen 170.

[0067) Additional food ingredients can be introduced to the partially dried food 140 that exits the first dryer 110. The one or more additional food ingredients- that can be introduced can be selected from the group consisting of an alcohol, a herb, garlic, ginger, saffron, onion, a colouring agent, a phenol, a polyphenol, a fragrant essential oil, an aromatic vegetable organic matter, a bacteria, and a food compatible compound. Preferably, the introduction of one or more food ingredients to the partially dried food occurs after the screening of the partially dried food 140.

[0068] In preferable embodiments, the first dryer 100 can have a higher capacity compared to the second dryer. In certain embodiments, the first dryer can be about double or more than the capacity of the second dryer 120.

[0069] A number of other advantages can be achieved through the described method and system for drying food. [0070] In particular, a higher level of digestible nutrients can be achieved by the described method and system compared to a method and system using a single drying step.

[0071] Additionally, it has been found that the residual moisture content protects the nutrient quantities and the digestibility of the partially dried food. In certain embodiments, up to 20% more nutrients with high digestibility can be expected than a single dryer. In particular, as the partially dried food exits the first dryer 1 10, a water film of the partially dried food provides protection in the gentler second drying process.

[0072] Additionally, certain embodiments can achieve higher levels of evaporation in the order of 15% to 25% than traditional processes and therefore provides higher energy efficiency.

[0073] The ability of the first dryer 1 10 to operate at higher temperatures on the incoming food also creates a condition whereby tissue is able to be blasted and separated from bone, thus creating partially dried food which can be screened of bone so as to produce dried food having lower ash. In fact the greater the temperature differential between the temperature of the food and the temperature of the first dryer, the greater the capacity of the bone to flesh separation. This process can also be performed with vegetable matter where fibre from intravascular bundles can be separated from the cellular material. In one form, the food can be cooled prior to being partially dried during the first drying step in order to increase the separation process.

[0074] With the low temperature in the second drying stage, the partially dried food is able to have an oil content up to 50% per weight without the food or partially dried igniting. This configuration allow such a method and system to commercially produce dried full fat meat, fish and poultry meals.

[0075] Due to the low temperature of the second dryer 120, oils, fats, proteins and other volatile substances should not burn, thus reducing the odour of emissions of the second dryer 120. Additionally, the water film produced in the first dryer 1 10 results protects these volatile substances from separating.

[0076] Additionally, the encapsulation of the food with a lipid bonding is enhanced with the two stage drying. This reduces the capacity of the meal to oxidise thus again reducing odours normally associated with malodourous material.

[0077] Furthermore, dust issues are significantly reduced and the remediation equipment needed to suppress these emission is generally not expected to be required. This thereby is expected to the capital cost for dust suppression equipment by about 50% compared to single phase drying systems.

[0078] Advantageously, in the event that the second dryer 120 operates at a temperature of about 50°C, the occurrence of dust explosions can be reduced.

[0079] Furthermore, the first drying step can provide better control for stabilising oxidising materials by removing any volatiles such as free fatty acids. This makes stabilization of the meal more effective not only because the thermodynamic conditions are lower but because some separation shall include material with higher free fatty acids.

[0080] Encapsulation of meals can be better achieved with reduced application of encapsulation agents if the first drying step is conducted without the need for these chemicals and that the addition of the chemicals is withheld until their food processed from the first dryer 1 10 is to be introduced into the second stage dryer with a more delicate thermodynamic profile.

[0081] As the second dryer 120 can operate at very low temperatures, egg membrane can be separated from the shell allowing for the production of a high nutrient dried food. The same process can be conducted with shellfish such as mussels, oysters, and clams where the shell can be separated from the attached meat. [0082] The ability of the second dryer 120 to operate at very low temperatures shall allow for combustible oils and also delicate essential oils to be introduced into the meal before the second stage drying is required. This so that accurate and properly formulated fat content of meals can be achieved. Further there is the capacity to enhance the nutrient value of the ration by introducing other delicate ingredients.

[0083] Additionally, as the second dryer 120 can operate at a low temperature of under about 50°C and the food can be exposed for a short time exposure period of under about 5 seconds, the second dryer 120 can dry partially dried food to increase quantities of nutraceuticals, phenols, including beta carotenoids and vitamins from most vegetable and animal products compared to traditional methods.

[0084] Furthermore, as the second dryer 120 can operate at low temperatures of under about 40°C and the food can be exposed for a short time exposure period of under about 4 seconds, yeasts and other growing products can be dried without damage to the food.

[0085] Due to the system providing extra drying capacity compared to traditional drying systems, a reduction in floor space of about 20% can be achieved. This is primarily as a result of having the primary dryer operate at temperatures far in excess of the normal range which can be used for drying food.

[0086] Additionally, increased product yields can amount to 2-4 percentile points due to reduced losses in the form of dust and air emissions.

[0087] Gelatinization of carbohydrates can also be better controlled using the described system and method whilst not attaining caramelisation phase due to the low operating temperature of the second dryer 120.

[0088] Shelf life of the dried product can also be increased using the described method and system due to increased lipid bonding. [0089] Improved dried food can also be achieved using the described method and system due to concentrates of nutrient and nutraceuticals are attained when foreign matter is removed by screening in between drying stages.

• [0090] The food that can be dried using the above described method and system can include, but not limited to, organic by-products such as fish by-products, dairy byproducts (whey byproducts, butter milk byproducts, yoghurt by-products), crustacean by-products, meat by-products, poultry by-products, and plant matter, supermarket residuals or combinations thereof which are edible by animals or feed plants.

[0091] Optional embodiments of the present invention may also be said to broadly consist in the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0100] Although a preferred embodiment has been described in detail, it should be understood that many modifications, changes, substitutions or alterations will be apparent to those skilled in the art without departing from the scope of the present invention.

[0101] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0102] The present invention will now be described with reference to the following specific examples, which should not be construed as in any way limiting the scope of the invention. Examples

Example 1 - Preparation of dried food

[0103J A sample of blood meal was dried (drying the food at a temperature of 450°C in the first drying step for a 4 second time period and drying the partially dried food at a temperature of 250°C for a 4 second time period). Results are shown in Figure 3. A high percentage of digestible protein and an increased level of nutrients such as Lysine, Methionine and Cystine were detected.

Example 2 - Comparison of different methods of drying food

[0104] A sample food was dried (AKT-KIX: drying the food at a temperature of 450°C in the first drying ste for a 4 second time period and drying the partially dried food at a temperature of 250°C for a 4 second time period). As a comparison other drying methods of the same sample food were performed using standard drying method of a steam cooker (STANDARD MEAL - 1.5hrs at 100°C), and drying methods (LT 559 and LT 561) comprising drying at a low temperature of 370°C for 30 minutes and 60 minutes respectively. Average values of a rat digestibility analysis are shown in Figure 4. The results indicate that the true digestibility, the biological value and the net protein utilization are either comparable or better than the standard drying procedures.

Example 3 - Comparison of different methods of drying food

[0105] A sample food was dried (KIX meal: drying the food at a temperature of 450°C in the first drying step for a 4 second time period and drying the partially dried food at a temperature of 250°C for a 4 second time period). As a comparison an indirect steam dryer process (Indirect dried meal: 1.5hrs at 100°C) and low temperature drying process (Direct dried meal: 30 minutes at 370°C) was applied to the sample food. Average values of a rat digestibility analysis are shown in Figure 5. The results indicate that the true digestibility, the biological value and the net protein utilization are either comparable or better than the indirect and direct drying procedures.

Example 4 - Comparison of different methods of drying food [0106] A sample food was dried (KIX process: drying the food at a temperature of 450°C in the first drying step for a 4 second time period and drying the partially dried food at a temperature of 250°C for a 4 second time period). As a comparison, an indirect steam dryer process (1.5hrs at 100°C) and a traditional drying process using low temperature (30 minutes at 370°C) were performed upon the food sample. Results of the experiments are shown in Figure 6. Increased levels in fat were detected compared to the steam dryer process and the traditional drying process. The remaining results are either comparable or better than the steam dryer process and/or the traditional drying process.

Example 5 - Comparison of dried food

(0107] A sample of dried food (KIX Meal (Orange Roughy Frames)) produced at a temperature of 450°C in the first drying step for a 4 second time period and a temperature of 250°C being applied in the second drying step for a 4 second time period, was analysed for levels of Lysine, Methionine and Cystine. As a comparison, other dried food samples (Herring Meal, Anchovy Meal, White Fish Meal) were also analysed which were produced using a low temperature drying process (30 minutes at 370°C). Results of the comparison are shown in Figure 7. Elevated levels of Lysine, Methionine and particularly Cystine were detected compared to the commercial samples.

Example 6 - Comparison of different methods of drying food

[0108] A sample of food was analysed before and after the drying process (KIX: drying the food at a temperature of 450°C in the first drying step for a 4 second time period and drying the partially dried food at a temperature of 25 °C for a 4 second time period). As a comparison, samples of food were analysed before and after the application of a pressure cooker drying process and a single dryer operating at 400°C for 1 hour. Results of the analysis are shown Figure 8. The loss of Vitamin E was substantially less in the dried food compared to the cooker drying process and the single dryer.

Example 7 - Comparison of ash content for different methods of drying food

[0109] A sample food was dried (AKT meal: (the first drying step was performed at a temperature of 450°C for a 4 second time period and the second drying step was performed at a temperature of 250°C for a 4 second time period) and separated using a sieve test into three portions: a bone portion, an intermediate portion and a meal portion comprising the dried food. Ash content of each portion was analysed. As a comparison, the sample food was dried using the low temperature drying method (LT meal: 30 minutes at 370°C). Results of the analysis are shown in Figure 9. The yield of dried food (AKT meal) in the meal portion was substantially higher (i.e. approximately 40%) compared to the low temperature drying method (LT meal) despite the percentage of ash content being comparable.